THEORIES OF INDIVIDUALITY 31 



This change is fundamentally a transmission, not a 

 transportation, for it consists in the passage of a certain 

 energetic change and not in the bodily transportation of 

 substance.^ Such a process of transmission may be 

 compared to the spreading of waves in a pond from the 

 point where a stone is thrown into the water, although 

 it probably does not always or necessarily consist of a 

 series of rhythmical changes like the water waves. 



The question of the nature of the transmitted or con- 

 ducted excitation has been the subject of much investi- 

 gation and discussion, and many different attempts to 

 answer it have been made. Recent investigation indi- 

 cates, however, that whatever its exact nature, it 

 involves an increase in metabolic activity. It seems 

 in fact to be a wave of increased chemical activity 

 spreading from the point of origin much as a wave spreads 

 in a pond. The question of the relation of the electrical 

 and chemical changes observed in the transmission of 

 excitation in protoplasm does not concern us here. 

 The fact of transmission and the increase in metabolic 

 activity in connection with it are the important points 

 for the present purpose. 



The transmission of excitations is one of the char- 

 acteristic features of living protoplasm, and undoubtedly 

 occurs to a greater or less extent in all protoplasm. In 

 its simplest form it is perhaps little more than a spread- 

 ing or irradiation to a greater or less distance of the 

 change produced at the point of origin, but in its most 



^ It should perhaps be noted that from the standpoint of current 

 physico-chemical theory transmission itself may be regarded as 

 molecular, atomic, ionic, or electronic transportation. Nevertheless, 

 the differences between such transportation and the transportation 

 in mass of substances is sufficient to warrant the distinction made. 



